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|標題:||Chloro(N-p-nitrobenzoylimido-meso-tetraphenylporphyrinato)iron(III): a high-spin complex||作者:||Chen, C.H.
|關鍵字:||metal-complexes;meso-tetraphenylporphyrin;molecular-structure;crystal-structure;epr spectroscopy;iron;porphyrins;proteins;ligands;bond||Project:||Journal of the Chemical Society-Dalton Transactions||期刊/報告no：:||Journal of the Chemical Society-Dalton Transactions, Issue 15, Page(s) 3001-3006.||摘要:||
The crystal structures of diamagnetic (methanol)(N-p-nitrobenzoylimido-meso-tetraphenylporphyrinato) zinc(II) methanol solvate Zn(N-p-NCOC6H4NO2-tpp)(MeOH).MeOH [or 4( MeOH).MeOH] and paramagnetic chloro-(N-p-nitrobenzoylimido-meso-tetraphenylporphyrinato)iron(III) Fe(N-p-NCOC6H4NO2-tpp) Cl (5), were determined. Both are pentacoordinate complexes where the p-nitrobenzoylimido (NNB) moiety is inserted into a zinc-pyrrole (or iron-pyrrole) bond. The coordination geometry of the zinc (or iron) center is best described as a distorted trigonal bipyramid with the N(2), N(5), and O(4) [or N(2), N(5), and Cl(1)] atoms lying in the equatorial plane. The plane of the three pyrrole nitrogen atoms [i.e., N(1), N(2) and N(3)] strongly bonded to Zn2+ in 4(MeOH).MeOH (or Fe3+ in 5) is adopted as a reference plane, 3N. The porphyrin ring is severely distorted and the pyrrole ring N( 4) is bonded to the NNB ligand making a dihedral angle of 30.0degrees (or 27.8degrees) with the 3N plane for 4(MeOH).MeOH (or 5). Solid state magnetic susceptibility and the effective magnetic moment data were measured for 5 from 300 to 5 K. In the higher temperature range (T > 50 K), the effective magnetic moment is constant and is equal to 5.87 mu(B). This mu(eff) value confirms that there is a high-spin ferric (S = 5/2) state for the iron atom in 5. The g values of 9.5 +/- 0.4, 4.2 and 1.1 measured from X-band EPR spectra were also consistent with a high-spin ferric iron in 5. The magnitude of zero field splitting, D, and the rhombicity parameter, lambda (E/D), in 5 were determined approximately as 0.79 cm(-1) and 0.29, respectively, by EPR spectroscopy and paramagnetic susceptibility measurements.
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